PI3 kinases p110α and PI3K-C2β negatively regulate cAMP via PDE3/8 to control insulin secretion in mouse and human islets.
PI3 kinases p110α and PI3K-C2β negatively regulate cAMP via PDE3/8 to control insulin secretion in mouse and human islets.
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DOI：
10.1016/j.molmet.2016.05.003
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发表时间：
2016-07
影响因子：
8.1
通讯作者：
MacDonald PE
中科院分区：
文献类型：
--
作者：
Kolic J;Manning Fox JE;Chepurny OG;Spigelman AF;Ferdaoussi M;Schwede F;Holz GG;MacDonald PE
内分泌胰腺中的磷脂酰肌醇-3-OH激酶（PI 3 K）信号传导有助于血糖控制。然而，PI 3 K调节胰腺β细胞胰岛素分泌的机制知之甚少。因此，我们的目标是双重的;确定急性PI 3 K抑制增强葡萄糖刺激的胰岛素分泌（GSIS）的信号传导途径，并检查该途径在2型糖尿病（T2 D）供体胰岛中的作用。用PI 3 K和/或磷酸二酯酶（PDE）抑制剂处理来自小鼠和非糖尿病或T2 D人类供体或INS 832/13细胞的分离胰岛。用siRNA敲低PI 3 K-C2 β的表达。我们测量了胰岛素释放、单细胞胞吐、细胞内Ca 2+反应（[Ca 2 +]i）和Ca 2+通道电流、细胞内cAMP浓度（[cAMP]i）以及cAMP依赖性蛋白激酶A（PKA）和蛋白激酶B（PKB/AKT）的活化。非特异性PI 3 K抑制剂渥曼青霉素放大GSIS，提高[cAMP]i并激活PKA，但在T2 D胰岛中没有作用。特异性PDE亚型的直接抑制证实了PDE 3（在人类和小鼠中）和PDE 8（在小鼠中）在PI 3 K下游的作用，并恢复了T2 D胰岛的葡萄糖反应性。我们暗示II类PI 3 K催化亚型PI 3 K-C2 β通过限制β细胞胞吐作用在该效应中发挥作用。PI 3 K通过人胰岛中的PDE 3限制GSIS。虽然抑制p110α或PIK-C2β信号传导本身可能促进营养素刺激的胰岛素释放，但我们现在认为这种信号传导途径在T2 D供体的胰岛中受到干扰。PI 3 K通过人胰岛中的PDE 3和小鼠胰岛中的PDE 3/8限制GSIS。PI 3 K抑制不增加来自T2 D供体的胰岛中的GSIS。PDE抑制恢复来自T2 D供体的胰岛中的葡萄糖响应性。PI 3 K-C2 β在限制β细胞胞吐中起重要作用。
Phosphatidylinositol-3-OH kinase (PI3K) signalling in the endocrine pancreas contributes to glycaemic control. However, the mechanism by which PI3K modulates insulin secretion from the pancreatic beta cell is poorly understood. Thus, our objective was two-fold; to determine the signalling pathway by which acute PI3K inhibition enhances glucose-stimulated insulin secretion (GSIS) and to examine the role of this pathway in islets from type-2 diabetic (T2D) donors. Isolated islets from mice and non-diabetic or T2D human donors, or INS 832/13 cells, were treated with inhibitors of PI3K and/or phosphodiesterases (PDEs). The expression of PI3K-C2β was knocked down using siRNA. We measured insulin release, single-cell exocytosis, intracellular Ca2+ responses ([Ca2+]i) and Ca2+ channel currents, intracellular cAMP concentrations ([cAMP]i), and activation of cAMP-dependent protein kinase A (PKA) and protein kinase B (PKB/AKT). The non-specific PI3K inhibitor wortmannin amplifies GSIS, raises [cAMP]i and activates PKA, but is without effect in T2D islets. Direct inhibition of specific PDE isoforms demonstrates a role for PDE3 (in humans and mice) and PDE8 (in mice) downstream of PI3K, and restores glucose-responsiveness of T2D islets. We implicate a role for the Class II PI3K catalytic isoform PI3K-C2β in this effect by limiting beta cell exocytosis. PI3K limits GSIS via PDE3 in human islets. While inhibition of p110α or PIK-C2β signalling per se, may promote nutrient-stimulated insulin release, we now suggest that this signalling pathway is perturbed in islets from T2D donors. PI3K limits GSIS via PDE3 in human islets and PDE3/8 in mouse islets. PI3K-inhibition does not augment GSIS in islets from T2D donors. PDE inhibition restores glucose-responsiveness in islets from T2D donors. PI3K-C2β plays a significant role in limiting beta cell exocytosis.